Stabilizing solution of tetra-alkyl lead compounds



Patented Dec. 1, 1942 UNITED a G SOLUTION F TETRA-ALK LEAD COMPOUNDS Troy Lee Cantrell, Lansdowne, and Carlton Louis Suplee, Maivern, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa, a corporation of Pennsylvania No Drawing.

1940, Serial No. 316,686.

Original application January 31,

Divided and this application March 31, 1942, Serial No. 437,086

4 Claims.

This invention relates to stabilizing solutions of tetra-alkyl lead compounds; and it comprises a method of stabilizing such solutions,particulartendency of the gasoline to cause knocking in high compression gasoline engines. The amount of tetra-alkyl lead compound added to a gasoline depends upon the nature of the gasoline and the desired antiknock rating. Tetra-ethyl lead is customarily added to the gasoline in the form of a concentrate called ethyl fluid" which is a solution containing a mixture of tetra-ethyl lead, alkyl di-halide (e. g. ethyl di-bromide or ethyl Iii-chloride or both) and a small amount of a dye to impart a distinctive color to the gasoline. The function of the alkyl di-halides is to limit the formation of lead oxide from tetra-alkyl lead in the cylinders of the engine by forming volatile halides of lead which are carried out in the exhaust. The ethyl fluid is added to the gasoline in a quantity sufficient to produce the desired antiknock rating and in some cases a relatively small amount may be required, while, in other cases, for example, in the preparation of certain aviation grades of gasoline, a relatively large amount may be added. Gasoline to which a large amount of tetra-ethyl or other tetra-alkyl lead has been added is often referred to as a heavily leaded" gasoline.

Although tetra-aikyl lead compounds, and, in

particular tetra-ethyl lead, are particularly emcient for imparting anti-knock properties to gasoline, their employment is not entirely free from disadvantage. For one thing, leaded gasoline tends to develop a hazy appearance upon standing; particularly in the presence of strong sunlight. For example, in direct sunlight in the summer time, ethyl gasoline may develop a perceptible haziness after an hour or two of exposure, and longer periods of exposure result in a very marked haziness and precipitation occurs. This phenomenon is also sometimes observed in the ethyl fluid itself.

The formation of haze in'gasoiine is objectionable because the gasoline is not as marketable as a clear product; customers prefer a product which is crystal clear. A further and perhaps more important objection is that a reduction in the octane rating of gasoline is frequently associated with haze formation. Also damage is like- 1y to occur in the fuel lines and carburetor. The development of haze in ethyl fluid itself is also objectionable, because when a hazy ethyl fluid is blended with gasoline to form ethyl gasoline, the haze is introduced into the fuel with all its attendant disadvantages.

An obj ect achieved by this invention is to provide solutions of tetra-alkyl lead compounds, such as ethyl fluid and ethyl gasolines, which are stabilized against haze formation. We have found that haze formation in solutions of tetraethyl lead compounds such as ethyl fluid and ethyl gasoline, can be very materially reduced,

by incorporating in such solutions small quanti-.

ties, proportioned on the amount of tetra-alkyl lead compound in solution, of a compound having the formula and known as benzalaniline.

Benzalaniline may be added with advantage to solutions generally of tetra-alkyl lead compounds and more particularly to all types of leaded gasoline. the benzalaniline in solutions of tetra-alkyl lead compounds is not critical. It may be incorporated in the ethyl fluid at any stage durin the preparation thereof, or it may be incorporated in the gasoline priorgto the addition of ethyl fluid, along with the ethyl fluid or subsequent to blending the ethyl fluid with the gasoline.

Even very small quantities of benzalaniline are suflicient to exert a substantial stabilizing efi'ect against light in fluids containing tetra-alkyl lead compounds. In general with higher percentages of tetra-alkyl lead compound, higher amounts of benzalaniline are required. Within the range of about 0.01 to about 1 per cent by weight of tetraethyl lead in gasoline, a substantial stabilizing effect is exerted by from about 3 to about pounds of benzalaniline per thousand barrels of gasoline. Within the range from about 0.02 to about 0.40.per cent by weight of tetravethyl lead in solution, which represents a commercial range, it is advantageous to employ from about '10 to about 40 pounds of, benzalaniline per thousand barrels of gasoline. Such amounts will exert a marked stabilizing effect against light and will The. manner of incorporating I of the gasoline.

produce a commercial ethyl gasoline which is satisfactorily stable to light under the usual conditions of exposure.

The application of benzalaniline to the stabilization of solutions of tetra-alkyl lead com; pounds againsthaze formation is not limited to leaded gasoline and it may be incorporated directly in the ethyl fluid with advantage. When benzalaniline is incorporated in the tetraalkyl lead concentrate, it stabilizes the concentrate during storage and shipment, and the stabilized concentrate containing the benzalaniline can then be added to gasoline to impart thereto both anti-knock properties and resistance to haze formation. In such case the amount of benzalaniline incorporated in the ct fluid is generally somewhat greater than is required for stabilization of the concentrate so that by the addition of the usual small amount of ethyl fluid to the gasoline a suitable stabilizing amount of benzalaniline will be incorporated in the gasoline. Generally from 1 to 10 per cent byweight, based on the tetra-ethyl lead, of benzalaniline very satisfactorily stabilizes commercial-tetraethyl lead concentrates, such as ethyl fluid and on adding the stabilized concentrate to" gasoline to produce ethyl gasoline, a satisfactorily stabilized ethyl gasoline is obtained.

The benzalaniline of our invention in addition to its stabilizing properties has other properties which particularly recommend it for this use. It does not adversely affect the oxygen stability of thegasoline. Samples of cracked ethyl gasoline containing benzalaniline -have been aged and tested for oxygen stability and by the copper dish method for gum formation. The presence of the benzalaniline did not promote either oxygen instability or gum formation. It is non-corrosive to common packaging materials such as steel, zinc, copper and tin and is compatible with the dyes commonly used in ethyl gasoline to give it a distinctive appearance. It is sufliciently soluble in'ggasoline to accomplish the intended stabilization. Furthermore it is insoluble in water, which is-a distinct advantage because contact with water will not result in leaching the stabilizer out Continued storage of gasoline containing benzalaniline does not affect its stabilizing properties. Also benzalaniline can be readily prepared from compounds available on the market at a relatively low cost, and its mode of preparation is simple and inexpensive.

The following specific example will serve to 11- lustrate the excellent haze"inhibiting properties of benzalaniline.

Example-Ethyl gasoline containing 0.1 per cent by weight of tetra-ethyl lead (added in the form of ethyl fluid comprising tetra-ethyl lead.

ethylene di-bromide and a dye) was treated with benzalaniline in the proportion 0120 pounds oi the latter per 1000 barrels-of gasoline. The resulting solution was exposed for 5 hours to simlight and the appearance of the gasoline was noted. At the end of the 5' hours exposure there was a small degree of haziness but a great improvement over the appearance of the same gasoline containing no benzalaniline. This was considered to be a fair stabilization.

While our invention has been described herein with reference to certain specific embodiments and specific examples thereof, we do not intend that our invention shall be limited to such embodiments and examples except as hereinafter defined in the appended claims. 1

What we claim is: 1. A method of producing a light-stable solution of a tetra-alkyl lead compound, which com- .prises incorporating in said solution benzalaniline in amount suflicient to inhibit the formation.

motor fuel benzalaniline in an amount corresponding to 0.01 to 1.0 per cent by weight of the tetra-alkyl lead compound. I

4. As an improved anti-knock motor fuel stable to light, a gasoline containing 0.02 to 0.4 per cent by weight of tetra-ethyl lead and about 10 to 40 pounds of benzalaniline per thousand barrels of gasoline.

TROY LEE CANTRELL. CARLTON LOUIS SUPLEE. 

